The utilization of light energy and the principles of physics involved therewith for purposes of examination and analysis of living tissue, in particular human tissue, is rapidly becoming recognized as a highly promising and useful methodology. One particularly advantageous such modality is described in my earlier, co-pending application Ser. No. 542,022, now U.S. Pat. No. 4,570,638, in which preferred embodiments and concepts are disclosed for carrying out such optical (i.e., light-physics) procedures, in the in vivo examination of human anatomy, in particular diagnostic breast examination. Reference is made to such co-pending application for a more complete discussion and disclosure of the apparatus and methodologies involved (such application being incorporated herein by reference).
One aspect or attribute of the methods and apparatus disclosed in the above-mentioned co-pending application comprises a manually-operated optical instrument by which light-response data is obtained from the living human tissue being examined. That instrument, which may be referred to as a "probe" (although not in a limiting sense), comprises basically a pair (or more) of probe terminals or active operating portions which are movable relative to one another for use in examination procedures by placing the selected portion of the body between the two such terminal or operative portions and bringing the latter close enough together to gently bear against opposite sides of the examination area. At least one of the terminal portions has a light-emitting member or element, for example, the end of a fiber optic bundle or cable, and at least one other such probe terminal includes at least one light-receiving sensor, detector, or other "receptor". In general, the instrument operates by pulsing light energy from the emitting element and detecting such energy, after dispersion, "scatter", and other such effects within the tissue under examination, at the sensor or collector located in the other part of the probe. While it will be understood that the actual nature of the two (or more) probe terminal portions is considerably more comprehensive than the apparatus just described, including for example, other light-sensors or collectors located at other positions as well as other possible light sources and/or positions, the basic nature of the apparatus is generally as just described.
In the use of such optical response instrumentation, it is inherently of the greatest importance that the response data which it produces be and remain consistent and comparable, and remain so throughout the useful life of the instrument in generating data for evaluation. That is, the sending and receiving characteristics of the light source and light receptors used in any two given different instruments may and probably will be at least somewhat different, and will probably change with time and usage as well. The same is true with respect to the electronic components generally, used in the data-conditioning and processing circuits, etc. Thus, if reliable data is to be obtained, and if that data is to be meaningfully compared with other data taken at different points in time and/or by different instruments, it is essential to provide a way in which correlation may be assured for all such data, e.g., a way in which calibration of the sending and receiving characteristics of all such instruments may be reliably determined and maintained.